# 用户信息表结构
users = [
    ("user_id", "integer", "用户ID"),
    ("username", "string", "用户名"),
    ("gender", "string", "性别"),
    ("age", "integer", "年龄"),
    ("city", "string", "城市"),
    ("membership_level", "string", "会员等级"),
    ("registration_date", "timestamp", "注册日期"),
    ("last_login", "timestamp", "最后登录时间"),
    ("search_frequency", "integer", "搜索频率")
]